exam qs

Question 1

This question is about plant transport systems. box
0 6 . 1 Describe how water is transported from the soil to the atmosphere through a plant.

Answer 1

(absorbed from soil) by osmosis
through root hair (cells)

travels through xylem (vessels)
to the leaves

lost through stomata (to
atmosphere)

idea of driven by evaporation /
transpiration

Question 2

Explain one way sieve tube cells are specialised for their function.
Use Figure 6.

Answer 2

have pores in the end walls

(so) dissolved sugars / food /
contents can move from cell to
cell

Question 3

What does the structure of the companion cells suggest about the process that moves
dissolved sugars through the phloem tissue?
Give a reason for your answer.

Answer 3

any one from:
(the process):
* requires energy
* is an active process
* uses active transport

(reason) cells have many
mitochondria

Question 4

Describe why it is important that dissolved sugars are moved both upwards and
downwards in a plant.

Answer 4

-sugars are made in the leaves
by photosynthesis

-all cells / tissues need sugar for
respiration

-(sugars) transported to
meristems for growth / cell
division / mitosis

Question 5

The diagram shows some plants growing in a greenhouse on a hot summer’s day.
Which one of the following factors is most likely to limit the rate of photosynthesis at this time?
* carbon dioxide concentration
* light intensity
* temperature
Factor ______________________________________________
Explain the reason for your answer.

Answer 5

carbon dioxide concentration
1
since atmospheric concentration very low / value give e.g. 0.03%

1
temperature high

1
light intensity high

Question 6

The graph shows how the rate of photosynthesis is affected by different conditions
(a) What patterns can you find from this graph?

Answer 6

+ light = + photosynthesis

+ light = + photosynthesis to a limit
limit depends on temp/CO2 levels

+ CO2 = + photosynthesis

+ temp = + photosynthesis

Question 7

(b) How the graph info useful could this information be to a grower using glasshouses? Give reasons for
your answer.

Answer 7

need to raise optimum levels
when one other raised
to get max/economic yield

Question 8

If the chemical reactions in the leaf were not stopped, the amount of starch would decrease. Why?

Answer 8

The starch could be broken down into sugar.

Question 9

What colour would the white part of the leaf go with iodine solution?

Answer 9

orange/ brown

Question 10

Why is there more stomata on the lower surface of the leaf

Answer 10

Cooler around the lower surface, more humid around lower surface, so less evaporation.

Question 11

ethanol is flammable the student wore safety goggles when testing the lead for starch give one other safety precaution

Answer 11

avoid using a naked flame near the ethanol, as it is flammable.

Question 12

Plants are grown in glasshouses to protect them from the weather or extend the growing season.
In winter, when days are shorter, glasshouses are heated to keep the enzyme reactions in plants at optimum rates.
What else should a grower do to make sure that the plants are photosynthesising at the optimum rate? Give a reason for your answer.

Answer 12

provide (more) light
provide (more) CO2
provide (plenty of) water
if any one of these is low it will limit the reaction